The sterilization operation is typically carried out when the medical instruments are still in the packaging, such that said instruments are kept sterile until they are opened. The sterilization means commonly used are gamma-irradiation, or the use of ethylene oxide gas, of steam or of formaldehyde vapor, which pass through the pores of the material so as to sterilize the instruments or prostheses contained in the packaging.
Packaging for medical instruments or prostheses is generally made up of a rigid or pseudo-rigid or flexible part, which can take substantially the shape of the medical object under consideration, on which a heat-sealing substrate is heat-sealed. The rigid or pseudo-rigid or flexible part is, for example, thermoformed. This packaging is usually opened where the sealing is located.
Such packaging, and more particularly the heat-sealable material used to make the seal, must generally meet several criteria with a view to its specific use. Thus, in addition to its heat-sealing properties, the material should advantageously be a breathable material, namely exhibit appropriate permeability for enabling the sterilization operation by allowing the sterilizing agent, for instance ethylene oxide, steam or formaldehyde vapor, to penetrate, while at the same time preventing contamination after sterilization. This packaging material may exhibit the functions required to allow it to be printed.
Moreover, in order to allow aseptic opening, the material must have properties of resistance to delamination when the packaging is opened.
Finally, the strength of the material must be sufficient to protect the objects packaged, and to withstand any perforation that might be caused by the content during transportation phases.
It is known practice to produce heat-sealable papers by coating the papers offline using a heat-sealable agent.
The offline coating multiplies additional labor and storage costs.
WO 98/24970 describes a peelable packaging comprising a heat-sealed reinforced paper coated with a layer of dielectric material formed from polyolefin polymers and copolymers.
Moreover, the publications EP 528 874, US 2007/0107381 or WO 99/32044, for example, describe the use of polyurethanes for their adhesive properties, in particular in laminates, or alternatively WO 03/086877 describes the use of polyurethanes for forming glue lines, including for sterilizable packaging. Polyurethane is also used in medical applications, for instance in U.S. Pat. No. 6,063,498.
There is a need to take advantage of fibrous materials which meet the requirements relating to their use in the medical field, which can be manufactured more economically.